High-resolution fast ion chromatography (FIC) measurements of chloride, nitrate and sulphate along the EPICA Dome C ice core

AbstractFast ion chromatographic (FIC) analysis of the first European Project for Ice Coring in Antarctica (EPICA) Dome C ice core (788m deep) was used to obtain high-resolution profiles for Cl–, NO3– and SO42–, spanning the last 45000 years. About 19 000 determinations for each component, with an average resolution of 4.0 cm, were performed in the field on continuously melted firn- and ice-core sections. the measured core covers the Holocene, the glacial/interglacial transition and about one-third of the last ice age. In the glacial period, mean concentrations of 93.8, 24.4 and 178.4 mg L–1 were calculated for Cl–, NO3– and SO42–, respectively. the mean levels significantly increase in the Last Glacial Maximum (LGM), when these compounds reach values of 149.6, 53.9 and 219.3 mg L–1. During the glacial/interglacial transition, the mean concentrations quickly decrease reaching the typical Holocene values of 19.1, 12.9 and 93.3 mg L–1, for Cl–, NO3– and SO42–, respectively. All species settle on Holocene-like values about 4000 years before the beginning of the warm period (from the isotopic curve) showing a low (chloride) and no (nitrate and sulphate) sensitivity to Antarctic Cold Reversal climatic change. the sulphate decrease is consistent with the dilution factor due to the higher accumulation rate in the interglacial conditions (about 2.5), suggesting no significant change in source intensity or transport efficiency occurred for this component. on the contrary, the Holocene values for chloride and nitrate, being much lower than those measured in the LGM, suggest a source-intensity and transport-efficiency enhancement during the LGM and/or a more effective fixing of HCl and HNO3 in the snow layers through the neutralizing effect of the higher atmospheric dust load.

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Evidence for a large surface ablation zone in central East Antarctica during the last Ice Age

Quaternary Research ◽

10.1016/s0033-5894(02)00014-5 ◽

2003 ◽

Vol 59 (1) ◽

pp. 114-121 ◽

Cited By ~ 26

Author(s):

Martin J. Siegert ◽

Richard C. A. Hindmarsh ◽

Gordon S. Hamilton

Keyword(s):

Ice Core ◽

Remote Sensing Data ◽

Ice Age ◽

Internal Layers ◽

Ice Flow ◽

Glacial Ice ◽

Ice Surface ◽

Ice Flows ◽

Last Ice Age ◽

The Hill

AbstractInternal isochronous ice sheet layers, recorded by airborne ice-penetrating radar, were measured along an ice flowline across a large (>1 km high) subglacial hill in the foreground of the Transantarctic Mountains. The layers, dated through an existing stratigraphic link with the Vostok ice core, converge with the ice surface as ice flows over the hill without noticeable change to their separation with each other or the ice base. A two-dimensional ice flow model that calculates isochrons and particle flowpaths and accounts for ice flow over the hill under steady-state conditions requires net ablation (via sublimation) over the stoss face for the predicted isochrons to match the measured internal layers. Satellite remote sensing data show no sign of exposed ancient ice at this site, however. Given the lack of exposed glacial ice, surface balance conditions must have changed recently from the net ablation that is predicted at this site for the last 85,000 years to accumulation.

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A 60-year ice-core record of regional climate from Adélie Land, coastal Antarctica

The Cryosphere ◽

10.5194/tc-11-343-2017 ◽

2017 ◽

Vol 11 (1) ◽

pp. 343-362 ◽

Cited By ~ 11

Author(s):

Sentia Goursaud ◽

Valérie Masson-Delmotte ◽

Vincent Favier ◽

Susanne Preunkert ◽

Michel Fily ◽

...

Keyword(s):

High Resolution ◽

Sea Ice ◽

Interannual Variability ◽

Ice Core ◽

Ice Sheet ◽

Sea Ice Extent ◽

Antarctic Ice Sheet ◽

Ice Core Record ◽

Decadal Variations ◽

The Mean

Abstract. A 22.4 m-long shallow firn core was extracted during the 2006/2007 field season from coastal Adélie Land. Annual layer counting based on subannual analyses of δ18O and major chemical components was combined with 5 reference years associated with nuclear tests and non-retreat of summer sea ice to build the initial ice-core chronology (1946–2006), stressing uncertain counting for 8 years. We focus here on the resulting δ18O and accumulation records. With an average value of 21.8 ± 6.9 cm w.e. yr−1, local accumulation shows multi-decadal variations peaking in the 1980s, but no long-term trend. Similar results are obtained for δ18O, also characterised by a remarkably low and variable amplitude of the seasonal cycle. The ice-core records are compared with regional records of temperature, stake area accumulation measurements and variations in sea-ice extent, and outputs from two models nudged to ERA (European Reanalysis) atmospheric reanalyses: the high-resolution atmospheric general circulation model (AGCM), including stable water isotopes ECHAM5-wiso (European Centre Hamburg model), and the regional atmospheric model Modèle Atmosphérique Régional (AR). A significant linear correlation is identified between decadal variations in δ18O and regional temperature. No significant relationship appears with regional sea-ice extent. A weak and significant correlation appears with Dumont d'Urville wind speed, increasing after 1979. The model-data comparison highlights the inadequacy of ECHAM5-wiso simulations prior to 1979, possibly due to the lack of data assimilation to constrain atmospheric reanalyses. Systematic biases are identified in the ECHAM5-wiso simulation, such as an overestimation of the mean accumulation rate and its interannual variability, a strong cold bias and an underestimation of the mean δ18O value and its interannual variability. As a result, relationships between simulated δ18O and temperature are weaker than observed. Such systematic precipitation and temperature biases are not displayed by MAR, suggesting that the model resolution plays a key role along the Antarctic ice sheet coastal topography. Interannual variations in ECHAM5-wiso temperature and precipitation accurately capture signals from meteorological data and stake observations and are used to refine the initial ice-core chronology within 2 years. After this adjustment, remarkable positive (negative) δ18O anomalies are identified in the ice-core record and the ECHAM5-wiso simulation in 1986 and 2002 (1998–1999), respectively. Despite uncertainties associated with post-deposition processes and signal-to-noise issues, in one single coastal ice-core record, we conclude that the S1C1 core can correctly capture major annual anomalies in δ18O as well as multi-decadal variations. These findings highlight the importance of improving the network of coastal high-resolution ice-core records, and stress the skills and limitations of atmospheric models for accumulation and δ18O in coastal Antarctic areas. This is particularly important for the overall East Antarctic ice sheet mass balance.

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A simple conceptual model to interpret the 100 000 years dynamics of paleo-climate records

Nonlinear Processes in Geophysics ◽

10.5194/npg-17-585-2010 ◽

2010 ◽

Vol 17 (5) ◽

pp. 585-592 ◽

Cited By ~ 2

Author(s):

C. S. Quiroga Lombard ◽

P. Balenzuela ◽

H. Braun ◽

D. R. Chialvo

Keyword(s):

Large Scale ◽

Power Spectra ◽

Greenland Ice Sheet ◽

Ice Age ◽

Solar Cycles ◽

The Holocene ◽

De Vries ◽

Last Ice Age ◽

Paleoclimate Records ◽

Dominant Frequencies

Abstract. Spectral analyses performed on records of cosmogenic nuclides reveal a group of dominant spectral components during the Holocene period. Only a few of them are related to known solar cycles, i.e., the De Vries/Suess, Gleissberg and Hallstatt cycles. The origin of the others remains uncertain. On the other hand, time series of North Atlantic atmospheric/sea surface temperatures during the last ice age display the existence of repeated large-scale warming events, called Dansgaard-Oeschger (DO) events, spaced around multiples of 1470 years. The De Vries/Suess and Gleissberg cycles with periods close to 1470/7 (~210) and 1470/17 (~86.5) years have been proposed to explain these observations. In this work we found that a conceptual bistable model forced with the De Vries/Suess and Gleissberg cycles plus noise displays a group of dominant frequencies similar to those obtained in the Fourier spectra from paleo-climate during the Holocene. Moreover, we show that simply changing the noise amplitude in the model we obtain similar power spectra to those corresponding to GISP2 δ18O (Greenland Ice Sheet Project 2) during the last ice age. These results give a general dynamical framework which allows us to interpret the main characteristic of paleoclimate records from the last 100 000 years.

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Limited migration of soluble ionic species in a Siple Dome, Antarctica, ice core

Annals of Glaciology ◽

10.3189/1998aog27-1-371-377 ◽

1998 ◽

Vol 27 ◽

pp. 371-377 ◽

Cited By ~ 25

Author(s):

Karl J. Kreutz ◽

Paul A. Mayewski ◽

Sallie I. Whitlow ◽

Mark S. Twickler

Keyword(s):

High Resolution ◽

Sulfonic Acid ◽

Accumulation Rate ◽

Ice Core ◽

Ionic Species ◽

Sea Salt ◽

Methane Sulfonic Acid ◽

Simple Diffusion ◽

Siple Dome ◽

Annual Resolution

High-resolution (>10 samples a−1) glaciochemical analyses covering the last 110 years from a Siplc Dome, Antarctica, ire core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO3 − and Mg2+). The observed chemical migration may be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and more acidic summer (from high marine biogenic acid concentrations) layers, common at coastal siles such as Siplc Dome. Exact mechanisms to expla in the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are formed where none previously existed in each case. Initial migration of each species is both shallower and earlier at Siple Dome than at other sites in Antarctica where similar phenomena have been observed, which may be related to the relatively low accumulation rate at Siple Dome (~13.3 cm ice a−1). Migration appears to be limited to either the preceding or following seasonal layer for each species, suggesting that paleoclimatic interpretations based on dala with lower than annual resolution are not likely to be affected.

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A first chronology for the NEEM ice core

Climate of the Past Discussions ◽

10.5194/cpd-9-2967-2013 ◽

2013 ◽

Vol 9 (3) ◽

pp. 2967-3013 ◽

Cited By ~ 9

Author(s):

S. O. Rasmussen ◽

P. Abbott ◽

T. Blunier ◽

A. Bourne ◽

E. Brook ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Conductivity Measurement ◽

Ice Cores ◽

Monte Carlo Analysis ◽

Heat Diffusion ◽

Ice Age ◽

Age Difference ◽

Electrical Conductivity Measurement ◽

Volcanic Origin

Abstract. A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the Electrical Conductivity Measurement (ECM) and Dielectrical Profiling (DEP) records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide additional horizons used for the time scale transfer. A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard–Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age–gas age difference (Δage) has been reconstructed using a coupled firn densification–heat diffusion model. Temperature and accumulation inputs to the Δage model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from δ15N of nitrogen and high-resolution methane data during the abrupt onsets of interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, and based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed, providing the necessary basis for further analysis of the records from NEEM.

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In Anticipation of Extirpation

Environmental Humanities ◽

10.1215/22011919-8142231 ◽

2020 ◽

Vol 12 (1) ◽

pp. 113-131 ◽

Cited By ~ 1

Author(s):

Patrick D. Nunn

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Age ◽

Optimal Solutions ◽

The Holocene ◽

The Past ◽

Coastal Cities ◽

The People ◽

Northwest Europe ◽

Last Ice Age

Abstract As concern about sea level rise grows and optimal solutions are sought to address its causes and effects, little attention has been given to past analogs. This article argues that valuable insights into contemporary discussions about future sea level rise can be gained from understanding those of the past, specifically the ways in which coastal peoples and societies reacted during the period of postglacial sea level rise. For much of the Holocene, most continental people eschewed coastal living in favor of inland areas. In many places large coastal settlements appeared only after the development of polities and associated crosswater networks. Postglacial sea level rise affected coastal living in ways about which we remain largely ignorant. Yet, millennia-old stories from Australia and northwest Europe show how people responded, from which we can plausibly infer their motivations. Stories from Australia say the people have succeeded in halting sea level rise, whereas those from northwest Europe indicate that people have failed, leading to the drowning of coastal cities such as Ys (Brittany) and Cantre’r Gwaelod (Wales). This distinction is explained by the contrasting duration of postglacial sea level rise in these regions; around Australia, sea level stopped rising 7,000 years ago, while along many coasts of northwest Europe it has risen unceasingly since the last ice age ended. The nature of past human and societal responses to postglacial sea level rise holds important insights for the future.

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The origin of the 1500-year climate cycles in Holocene North-Atlantic records

Climate of the Past Discussions ◽

10.5194/cpd-3-679-2007 ◽

2007 ◽

Vol 3 (2) ◽

pp. 679-692 ◽

Cited By ~ 18

Author(s):

M. Debret ◽

V. Bout-Roumazeilles ◽

F. Grousset ◽

M. Desmet ◽

J. F. McManus ◽

...

Keyword(s):

Ocean Circulation ◽

Ice Core ◽

Ice Age ◽

Data Series ◽

Oceanic Circulation ◽

Solar Forcing ◽

The Holocene ◽

Relative Contribution ◽

Climate Cycles ◽

Wavelets Analysis

Abstract. Since the first suggestion of 1500-year cycles in the advance and retreat of glaciers (Denton and Karlen, 1973), many studies have uncovered evidence of repeated climate oscillations of 2500, 1500, and 1000 years. During last glacial period, natural climate cycles of 1500 years appear to be persistent (Bond and Lotti, 1995) and remarkably regular (Mayewski et al., 1997; Rahmstorf, 2003), yet the origin of this pacing during the Holocene remains a mystery (Rahmstorf, 2003), making it one of the outstanding puzzles of climate variability. Solar variability is often considered likely to be responsible for such cyclicities, but the evidence for solar forcing is difficult to evaluate within available data series due to the shortcomings of conventional time-series analyses. However, the wavelets analysis method is appropriate when considering non-stationary variability. Here we show by the use of wavelets analysis that it is possible to distinguish solar forcing of 1000- and 2500- year oscillations from oceanic forcing of 1500-year cycles. Using this method, the relative contribution of solar-related and ocean-related climate influences can be distinguished throughout the 10 000 Holocene intervals since the last ice age. These results reveal that the mysteriously regular 1,500-year climate cycles are linked with the oceanic circulation and not with variations in solar output as previously argued (Bond et al., 2001). In this light, previously studied marine sediment (Bianchi and McCave, 1999; Giraudeau et al., 2000), ice core (O'Brien et al., 1995) and dust records (Jackson et al., 2005) can be seen to contain the evidence of combined forcing mechanisms, whose relative influences varied during the course of the Holocene. Circum-Atlantic climate records cannot be explained by solar forcing, but require changes in ocean circulation, as suggested previously (Broecker et al., 2001; McManus et al., 1999).

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Air Content Of The Byrd Core And Past Changes In The West Antarctic Ice Sheet

Annals of Glaciology ◽

10.1017/s0260305500002901 ◽

1982 ◽

Vol 3 ◽

pp. 269-273 ◽

Cited By ~ 42

Author(s):

D. Raynaud ◽

I. M. Whillans

Keyword(s):

Stable Isotope ◽

Accumulation Rate ◽

Ice Core ◽

Ice Sheet ◽

Ice Cores ◽

Isotope Ratios ◽

Ice Age ◽

Gas Content ◽

Stable Isotope Ratios ◽

Antarctic Ice Sheet

Analyses of ice cores taken from the Antarctic ice sheet can provide information on the environmental conditions under which the ice was formed. New results from measurements of gas content and stable isotope ratios in the Byrd station ice core are discussed and interpreted in terms of past iceflow changes.165 selected ice samples from 32 different depth levels along the core were processed for total gas content V and stable isotope ratios. This large dataset is used to discuss the variability and significance of the values of V at different depths. The short term variations of V are mainly explained by heterogeneities of the pore volume when the firn pores close off.The general trends in the values of V with depth are then used to investigate the possibility of past changes in the ice sheet. They suggest near-steady flow during the past few tens of thousands of years and that a thickening of about 200 to 250 m occurred in this area of the ice sheet at the end of the last ice age. This thickening could be due to a change in the accumulation rate.

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Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core

Climate of the Past ◽

10.5194/cp-8-1839-2012 ◽

2012 ◽

Vol 8 (6) ◽

pp. 1839-1847 ◽

Cited By ~ 20

Author(s):

P. Vallelonga ◽

G. Bertagna ◽

T. Blunier ◽

H. A. Kjær ◽

T. J. Popp ◽

...

Keyword(s):

High Resolution ◽

Ice Core ◽

Ice Age ◽

Age Difference ◽

Glacial Period ◽

Annual Layer ◽

Chemical Impurities ◽

Dronning Maud Land ◽

Ice Core Records

Abstract. High-resolution measurements of chemical impurities and methane concentrations in Greenland ice core samples from the early glacial period allow the extension of annual-layer counted chronologies and the improvement of gas age-ice age difference (Δage) essential to the synchronization of ice core records. We report high-resolution measurements of a 50 m section of the NorthGRIP ice core and corresponding annual layer thicknesses in order to constrain the duration of the Greenland Stadial 22 (GS-22) between Greenland Interstadials (GIs) 21 and 22, for which inconsistent durations and ages have been reported from Greenland and Antarctic ice core records as well as European speleothems. Depending on the chronology used, GS-22 occurred between approximately 89 (end of GI-22) and 83 kyr b2k (onset of GI-21). From annual layer counting, we find that GS-22 lasted between 2696 and 3092 years and was followed by a GI-21 pre-cursor event lasting between 331 and 369 yr. Our layer-based counting agrees with the duration of stadial 22 as determined from the NALPS speleothem record (3250 ± 526 yr) but not with that of the GICC05modelext chronology (2620 yr) or an alternative chronology based on gas-marker synchronization to EPICA Dronning Maud Land ice core. These results show that GICC05modelext overestimates accumulation and/or underestimates thinning in this early part of the last glacial period. We also revise the possible ranges of NorthGRIP Δdepth (5.49 to 5.85 m) and Δage (498 to 601 yr) at the warming onset of GI-21 as well as the Δage range at the onset of the GI-21 precursor warming (523 to 654 yr), observing that temperature (represented by the δ15N proxy) increases before CH4 concentration by no more than a few decades.

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The EPICA deep ice cores: first results and perspectives

Annals of Glaciology ◽

10.3189/172756404781814500 ◽

2004 ◽

Vol 39 ◽

pp. 93-100 ◽

Cited By ~ 10

Author(s):

Bernhard Stauffer ◽

Jacqueline Flückiger ◽

Eric Wolff ◽

Piers Barnes

Keyword(s):

High Resolution ◽

Ice Core ◽

Ice Cores ◽

Chemical Compounds ◽

Conductivity Measurements ◽

Open Questions ◽

First Results ◽

Field Season ◽

Fast Ion ◽

Detailed Record

AbstractTwo deep ice cores are being drilled in Antarctica in the frame of the European Project for Ice Coring in Antarctica (EPICA). The Dome C ice core will provide more information about mechanisms of global climatic changes over several climatic cycles. The DML core, drilled at Kohnen station, will provide a detailed record over the last climatic cycle, which can be compared with Greenland records. The drilling at Dome C reached 3200 m depth during field season 2002/03, and the age of the ice at the bottom of the hole could be 900 000 years according to preliminary estimates. The depth at Kohnen station is 1564.6 m at present, corresponding to an age of about 55 000 years. Analyses along the top parts of both ice cores have provided interesting first results. A few selected results from these parts, mostly published already, are summarized. Only a few measurements are available from the deeper parts of both cores. Dielectric profiling and electrical conductivity measurements, performed in the field, provide continuous and high-resolution records concerning the acidity and the salt concentration of the ice. Continuous flow analyses and Fast Ion Chromatography also provide high-resolution records of several chemical compounds. These records give some clues as to the age scale of the EPICA Dome C ice core, but they also leave us with many open questions.

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